Bellamy ran his hands through my lucious brown hair, while I cupped his cheek which wasn't oily at all, and noticed he smelled like lavender and sunshine—

your characters are definitely not going to look perfect after spending about two months without showering. idk about you guys, but i look like a gremlin if i don't wash my hair every other day.

i'm not saying that you have to describe everyone smelling gross. you could include some minor details hinting to realism. like purple rings/bags under their eyes from lack of sleep, papery skin from insufficient nutrition, their hair tangled, sweating, oil on their face, etc.

octavia never had her hair pinned back in season 1, so she's the prime example of it. here's her in the pilot vs her by the end of the season

(and in season 5.... dear god. but for the sake of spoilers, let's move on)

for a male example, take murphy

i get that you may not want to touch on these things because we all have some weird instinct to keep our characters perfect, but at the same time, we have to remind ourselves that they're not.

don't be afraid to get your OC's dirty!! keep in mind that they're sleeping in tents on the grounds, constantly outside/working, and they've probably got some injuries on their faces. you don't have to go full-on survivor with this, but sometimes even a little bit goes a long way to keep it realistic